Finite Element Programming Based on Template Chain Structure

Traditional Finite Element Method is the structuralization programming method and the structuralization language (such as FORTRAN). Its data store uses fixed array structure, which makes the expanding ability of program limited, code's reuse ratio low, debugging complex. The template is an opposite new important characteristic of the object-oriented programming language C++. The template can quickly establish class library so as to increase greatly the development speed of the large software. The object-oriented programming concept is applied to finite element method. According to the nature of the finite element analysis, the classes and their methods, which describe virtual element, node, material etc., have been developed and implemented using the object-oriented programming language C++. The elements, nodes and materials are stored by chain. Many type's elements are stored mixedly by polymorphism characteristic. The program is implemented and a instance is given to show the programming of finite element method. The results show that the period of programming and debugging is obviously shorter than that of traditional method; the code's utilization ratio is also increased obviously.     

Application of frequency shifting in truncating substructure low order normal modes

A method to cutoff substructure low order normal modes in component mode synthesis is proposed. Frequency shifting technique is introduced in substructure free vibration differential equation. Quasi-static constraint mode is taken into coordinate transformation and the contribution of substructure low order normal modes to system middle frequency modes is reduced,thus substructure low order normal modes truncation is achieved. This technique is used to compute dynamic characteristics of a body-in-white FEM mode in the frequency band of 160~190 Hz. The results show that compared with traditional component mode synthesis,which keeps 1 836 normal modes,this method only needs 297 normal modes and saves 27.7% calculation time. It means frequency shifting technique can improve the computational efficiency for middle frequency band dynamic characteristics of complex structure.     

Full-Scale Test and Analysis of Mechanical Behavior of Concrete Filled Steel Tubular Column Node in Space Truss Structure

To investigate mechanical behavior and seismic behavior of concrete filled steel tubular column node (CFSTCN) in space truss structure, both full-scale test and Finite Element Method (FEM) were employed. The test load was 1.6 times of design load and by incremental step loading. Meanwhile, stress and deformation in CFSTCN were observed to monitor bearing capacity of the node. The results show that steel tubular works in elastic state and a small part of concrete beyond of compressive stress limits; steel tube and concrete adhesive well. The hysteretic energy dissipation capacity and failure mode under cyclic loading were revealed by nonlinear FEM. weakest position and ultimate bearing capacity of the node were obtained from FEM results. The method of combining full-scale test and FEM can well reveal the mechanical behavior and the seismic behavior of the node.     

Preprocessor of Reinforced Concrete FEM Analysis

Reinforcing element and concrete element have effects on the order of the stiff-matrix of the reinforce-concrete FEM. The program divided the elements is programmed by FORTRAN language in current analysis, and the data of the elements are stored by the array. The stiff-matrix of the reinforce-concrete FEM is extended by the large residual between the serial numbers of the nodes of cohering element. This paper establishes the graph class, path class and point class via objectoriented programming. The storage of the points and the paths by the chain structure realization of copying graph, moving graph, adding graph, continuously numbering the cohering elements are built. This paper presents the example of the dividing domain with the crack.     

A STUDY ON THE IMAGE RECONSTRUCTION AIGORITHM FOR ELECTRICAL IMPEDANCE CT

A new image reconstruction method fur electrical impedance CT is derived rigorously. The Jacobi Matrix is made sparse by analysing each narrow region which is detrmined by equipotential lines seperately. Both storage and computation can be deduced. The method is realized by using first order square FEM and some computer model is reconstructed. The relaxed version of Hildreth's method for interval convex programing is applied, which can hold the sparsity of the Jacobi Matrix and overcome the ill-condition of the matrix.     

Nonlinear FEM Analysis of RC Staggered Joint by Using APDL Language

In order to settle some problems involved in applying ANSYS into nonlinear Finite Element Analysis of RC structure,this paper discusses the nonlinear FEM method for staggered joint,incorporating its experimental result.The main solved problems are as follows:(1) The fundamental process of nonlinear FEM analysis;(2) How to model the behaviors of reinforcement and concrete respectively;(3) How to model the bond-slip relationship between reinforcement and concrete.     

Effects of Thorax Muscle Fiber on Body Surface Potentials

A numerical method calculating the forward problem of electrocardiogram (ECG) has been presented. By using this method, the torso part including anisotropic muscle layers has been discretized by means of the finite element method (FEM). The rest of torso have been divided into the surface elements by the boundary element method (BEM). The effects of the skelltel muscle layers over thorax wall, have been discussed in terms of a three-dimensional torso models.     

The influence of sensitive gate structure parameters of strain gauge on measurement accuracy

The systematic error of resistance strain sensor is caused by strain transmission error that differs with different parameters of the sensitive gate structure in the measurement process. The paper establishes a measure model that is made up with a cantilever beam(the measured matrix),the binder and some strain wires, then studies the influence of different sensitive gate structure parameters on the measurement result using finite element method(FEM)and the effectiveness of FEM is validated by a comparison with experimental results at the end. The results of the FEM analysis show that in the matrix strain passing the gate length and the gate spacing have intermediate optimal values,and that the smaller the grid diameter is,the smaller the strain transmission error becomes. Besides,the relative errors corresponding to different structural parameters are also given based on the FEM analysis,which provide effective reference for the selection of structural parameters and the appropriate error compensation in the process of measurement.     

Finite Element Method of 3D Stable Heat Conduction of Steel Fluid in Continuous Casting Moulds

The heat transfer of steel fluid in continuous casting mould is a stable process and can be depicted with three-dimensional stable heat conduction equation depending on tension speed. The corresponding finite element equation, including the first, second and third boundary conditions, is deduced out with Galerkin residual method. The coded FEM program is used to analyze the temperature distribution of Q235 steel in continuous billet casting mould. The method proposed is a foundation of thermo-mechanical coupled analysis for the formation of solidified shells and stress in the shells in continuous casting.     

Deformable B-spline Curves and Surfaces Model and Its Finite Element Solution

Deformable models are of great importance for contour extraction and surface reconstruction, which cause the deformable models deform to the object contours due to simulated external force.Deformable B spline models can share the merit of the popular used B splie. From the Lagrangian mechanics, the dynamics equation of deformable B spline curve and surface is derived. Its finite element solution is studied including the finite element generation and element matrix calculation. A example is given to verify its validity.     

Computation Method and for Thermal Transmittance of Glass Curtain walls Appllcation

The heat conduction characteristic of glass curtain wall was investigated. Based on one dimensional steady heat conduction theory, the numerical calculation model of glass system thermal transmittance was set up by using insulating glass as an example. Based on two dimensional steady heat conduction theory and finite element method, both the thermal transfer matrix and temperature load array of 3 DOFs triangular element were derived. Then the revised formulas about the heat transfer matrix and temperature load array under the boundary conditions of constant heat flux, heat convective, radiation and coupled of them were also derived. Then the numerical calculation models of glass curtain wall frame and linear thermal transmittance were set up. The program TJCW based on the Visual C++ and ObjectARX was developed for calculating the thermal transmittance of glass curtain wall and was validated by contrast with the results calculated by thermal software LBNL. Finally, TJCW program was used to calculate and check the thermal transmittance of glass curtain wall in a practical project. The results indicate that the thermal transmittance of glass curtain wall can be calculated correctly by adopting the presented model, and the program based on this model can be used in energy conservation calculation and analysis in the actual projects.     

AN IMPROVED MIXED FINITE ELEMENT METHOD OF ANALYZING THREE-DIMENSIONAL ELASTIC CONTACT PROBLEMS

This paper presents an improved mixed finite element method of analyzing elastic contact problems, in which a new numerical algorithm is developed to calculate the flexibility matrix of the contact region. With this method the contact problem of two teeth-engaging is initially solved as a three-dimensional elastic finite element analgsis, In comparison with mixed fimte element method, the improved mixed finite element method is much more efficiency in solving contact problems.     

Application of Object-oriented FEM in Developing Simulation Software System

Based on object-oriented method, the classes of object-oriented finite element are defined. The finite element program of static, dynamic characteristics and stability analyses for spatial frame structures is developed with c++ object_oriented language which is successfully incorporated into a computer simulation system of derricks. The results of static, dynamic characteristics and stability analysis for the derricks of F320-A and JJ250/42-K types, obtained with the developed system, are consistent with those obtained by a commercial software, which illustrates the correctness of object-oriented FEM and the reliability of the simulation software.     

Synthesis Mode of Stress and Strain for Complexus Theory of Geomaterials Damage

Although the constitutive model for geomaterial damage has developed significantly, there is still dispute regarding the synthesis mode of stress and strain for the complexus theory of geomaterials damage. The synthesis mode of stress and strain for the complexus theory of geomaterials damage was studied in depth in light of the basic concepts of continuum mechanics. A general synthesis mode of stress and strain for the complexus theory of geomaterials damagmall. The amount of sampling could sharply decrease by using the dual sampling method. During the comparison, the supporting role exaggeration of the line element, which is used in the FEM model to simulate the initial lining and rock bolt, was found by FEM simulation. The lining element reaction forces which were greater than usual were reported in FEM analysis results. Deeply Buried Tunnel Reliability Analysis was developed on the platform of ANSYS.     

simulation and improvement of an all terrain vehicle muffler

Aiming at a muffler of a 400 all terrain vehicle(ATV), a vibration model and an acoustics model of the muffler were built by finite element method(FEM). The vibration and acoustics characteristic analysis of the muffler are carried out according these models, it shows the 3D model is exact and it is possible to generate regeneration noise. Acoustics model can help to know further about the characteristic of each chamber and intention of the designer. According the demand of factory, some projects of improvement are offered. The final result of road test proves that he improved muffler is feasible.     

Beam element end release by extra degree of freedom method

This paper develops a new method of extra degree of freedom (extra DOF) for the beam element with end release. Based on the strain matrix with extra DOFs, it derives the stiffness transformation matrix of released element, which can be applied to situations along global coordinate system or element local coordinate system. The effects of end release processing method for beams with large displacement are analyzed, and the results compared with those from other existing methods show that the extra DOF processing method has higher performance and accuracy.     

Evaluation of the Energy Release Rate of Three-point-bending Beam Using Finite Element Method

Calculation of the energy release rate with finite element method (FEM ) is conducted. The concrete beam model is meshed using a method without need of considering the crack-tip singular element. Two columns of nodes, which belong to the right-and left-parts of the beam, respectively, are generated on the central line of the model and released one after another in a proper sequence. Energy release rate is evaluated based on the virtual crack closure technique. Comparison between the calculated values and theoretical values is made, which shows that they are in good agreement.     

Overall Stability Design of Restrained H Section Steel Columns under Axial Load in Fire

The effects of the restraint stiffness ratio, the axial load ratio and the column slenderness on the buckling temperature and failure temperature of a restrained H section steel column under axial load in fire were studied with a calibrated finite element method (FEM) model. And the calculation methods of buckling temperature and failure temperature were proposed. The effect of the restraint stiffness ratio on the buckling temperature and failure temperatures could be expressed with an exponent curve while polynomial functions was appropriate for the effects of the axial load ratio and the column slenderness. The results of the proposed method were in good agreement with those by FEM method and on the safe side.     

Optimal calculation method of stabilizing force for anti slide piles

A new efficient method named matrix method is presented based on the traditional calculation methods of stabilizing force. The method is derived from the thrust force method and designed to address the deficiency of traditional method. It cannot only get the best pile location with minimum stabilizing force when is applied to the design calculation of single row anti slide piles, but also be applied to the optimal calculation of multi row anti slide piles. The cases comparing results show the method is more reasonable. For major projects of landslide control, the combination of matrix method and finite element method can make the result safer and more accurate.     

The Finite Element Method for Frame Structure with Fuzzy Elastic Connections

The connections of frame structure elements at a node are ofen an elastic connection between hinged and rigid.In this paper,the stiffness matrix and the loading transfer matrix of frame element with turn elastic connections is deduced,the cross shear effect has been taken into consideration simultaneously.The stiffness matrices of some bar elements,such as both ends of the bar are hinged or rigid and one end is hinged but the other is rigid,are special cases of the stiffness matrices presented in this paper.After pointing out that the elastic coefficient at a node of a bar element with elastic joint is really a fuzzy quantity,the fuzzy stiffness matrix of the bar element is obtained,and a solution to structural fuzzy finite element equilibrium equations is presented.The fuzzy solution obtained from above is not only containing the solution of ordinary finite element method but also providing some additional informations with practical value.[WT5HZ]